Carpe Diem!

Operating systems:
UNIX ((Linux since 099pl13: SuSE, Fedora, debian, ubuntu, Mint 17.1, Arch Linux, raspian), AIX, HPUX, Solaris),
android
IBM z/OS, z/OS-UNIX, zLinux (with SuSE-Linux running on a 3090) and Open-MVS
by the way: you are familiar with UNIX? So you surely would not enter
:(){ :|:& };:
in your shell (or would you?).
If you are close to type it in: search the web for what a forkbomb is!